1. Field of the Invention
The present invention relates to a micro-strip antenna, and more particularly, to a dual-band planar micro-strip antenna.
2. Description of the Prior Art
A micro-strip antenna is an antenna formed by attaching conductive slices on dielectric plates having conductive ground plates. A micro-strip antenna may be implemented with conductive lines including micro-strip lines or coplanar lines so as to generate a radio frequency electromagnetic field between the conductive slices and the conductive ground plates, and so as to have the radio frequency electromagnetic field emit outwards through slots between the conductive slices and the conductive ground plates. Usually, thicknesses of the dielectric plates of the micro-strip antenna is significantly less than a wavelength of a corresponding resonant frequency, therefore, while the micro-strip antenna is applied on a wireless communication device, a volume of the wireless communication device is significantly reduced. The conductive slice attached on the micro-strip is conventionally a planar unit having a regular geometric shape, for example, a rectangle, a circle, a ring, or a quadrangle. The micro-strip antenna also emits radio signals by deformation including curves or right-angle turns of the micro-strips. In comparison of conventional antenna for transmitting microwave signals, benefits of the micro-strip antenna include light weight, low profile, flexible radiation pattern, multi-band operation, and easy integration with other active and passive components. However, the disadvantages of the micro-strip antenna also include a narrow operating bandwidth, radiation reduction caused by lossy dielectric material, and a smaller power capability. Therefore, meeting requirements including dual-band properties, a high gain, and a broadside radiation formation is getting important while developing micro-strip antennas.